The present invention relates in general to a motor vehicle braking system and, more particularly, the invention relates to a brake pressure regulation apparatus on a motor vehicle that has brake pressures which are controlled by at least one arbitrarily activated brake application apparatus.
Prior to the present invention, it has been known that in the brake system of a motor vehicle, or a combination of vehicles consisting of the motor vehicle and a trailer, the pressurization of either pneumatically or hydraulically-operated wheel brakes with brake pressure from one or more pressure sources, can be controlled by means of a brake application apparatus which can be activated arbitrarily by the operator of such vehicle. The brake application apparatus is activated by the driver, using his hands or feet, and controls the level of the brake pressure as a function of either the activation force or the activation distance, or possibly by a combination of both. In the case of a vehicle-combination or a trailer, the brake application apparatus contains an apparatus that is controlled by the brake pressure in the motor vehicle for the simultaneous control of the brake pressure to the wheel brakes of the trailer.
Components which make up the wheel brakes exhibit not only fabrication tolerances, but also fluctuations, as a result of the material characteristics of the materials used in them, for example, fluctuations of the coefficient of friction of the brake lining. In such a case, the wheel brakes on both sides of one axis and/or the wheel brakes of one or more front axles can produce, during application, an uneven braking force or braking torque, from those produced by the wheel brakes of one or more rear axles of the motor vehicle or of the trailer or of the vehicle-combination and/or the wheel brakes of the motor vehicle can exhibit such differences in relation to the wheel brakes of the trailer. This can occur, even when the same brake pressure is released by the brake application apparatus to all the wheel brakes involved.